Arctic's Icy Coastlines Retreat as Planet Warms

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In the high latitudes, climate change projections must take a new
factor into account: Ice. In the Arctic, the loss of sea ice is
likely to have dramatic repercussions, including greater erosion,
which can present problems for the people and economic activity
in this region, according to two new reports.

Sea ice is disappearing from Arctic waters at an unprecedented
rate — more rapidly than predicted by the most extreme
projections in the most recent assessment report by the
Intergovernmental Panel on Climate Change, according to the
researchers. [ Image
of eroding coastline ]

The rapid decline — 2010 had the
third smallest summer ice cover of the past 30 years —
suggests that human-caused climate change is being augmented by
natural fluctuations, said Volker Rachold, a researcher with the
Alfred Wegener Institute in Germany who contributed to two recent
reports on the Arctic coastline. "Otherwise, it would be
difficult to explain the rapid loss of sea ice we are seeing at
the moment," Rachold said.

Less sea ice means more open water, which means stronger waves
generated by wind. These, in combination with warming
temperatures and more storms, mean more erosion of coastlines.
Rising sea levels are also expected to enhance erosion. One of
the reports, a study published in the journal Estuaries and
Coasts, found an average rate of erosion of 1.6 feet (0.5 meters)
per year for the Arctic coast. It identifies the Laptev, East
Siberian and Beaufort seas as the areas with the highest rates of
erosion.

Icy coasts are vulnerable

Some coastlines are more vulnerable than others. Rocky shorelines
easily outlast the frozen sediments — the
permafrost coast — that lines Arctic terrain. Sixty-five
percent of the coastline facing directly into the Arctic Ocean,
and 34 percent of the world's coastline, are Arctic permafrost.

These sediments can be rich in ice, making them sensitive to
erosion, because warmer temperatures and waves wear away at them,
Rachold said.

Coastal erosion and warming temperatures — record high
temperatures extended across Greenland and the Canadian Arctic
last summer — could exacerbate global warming by releasing gas
hydrates contained in the permafrost. Gas hydrates are ice-like
crystals composed of water and gases, often methane, a greenhouse
gas like carbon dioxide; however, the implications of the release
of gas hydrates aren't fully understood, according to Rachold.

The human dimension

Permafrost sediments are often flat and low-lying, making them
good locations for settlements. Unfortunately, in some places,
erosion can vary up to 33 to 98 feet (10 to 30 meters) per year.
Storms are a particularly potent cause of erosion, according to
the second report, The
State of the Arctic Coast 2010. Both reports were prepared by
teams of international scientists.

Many Arctic communities have a history of dealing with retreating
land. Even so, some are in dire situations.

For example, Shishmaref is a community of indigenous Inupiaq
located on a barrier island in Northwest Alaska. The island, a
quarter of a mile wide and 3 miles in length, is made of fine
sand and permafrost. After watching both its northern and
southern shorelines steadily creeping inward, punctuated by
severe storms, the community decided to relocate to the mainland,
according to the Shishmaref Erosion & Relocation Coalition.
[ Climate
Change Redraws World Maps ]

Sea walls and other barriers are options for some communities,
but they are costly and funds are limited, the report says,
which points out that changes will also affect economic activity,
which in the Arctic focuses on extracting natural resources, such
as fishing.

Monitoring the Arctic coast should be a priority so people can
adapt to changes and make sure future development is sustainable,
according to the second report, which assesses the physical,
biological, social and policy dimensions of the effects of
climate change on the Arctic coasts.